Method of making an electrostatic chuck with reduced plasma penetration and arcing

ABSTRACT

A method of making an electrostatic chuck comprising positioning a plate into a channel in a body to form a plenum and inserting a dielectric component into an opening in the plate, where the dielectric component defines a portion of a passage from the plenum. Thereafter, depositing a dielectric layer covering at least a portion of the body and at least a portion of the plate to form a support surface. The dielectric layer is polished to a specified thickness. In one embodiment, the polishing process forms an opening through the dielectric layer to enable the dielectric component to define a passage between the support surface and the plenum. In another embodiment, at least a portion of the dielectric layer is porous proximate the dielectric component such that the porous dielectric layer and the dielectric component form a passage between the support surface and the plenum. In a further embodiment, a hole is formed through the dielectric layer and the hole in the dielectric layer and the dielectric component form a passage between the support surface and the plenum.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application contains subject matter that is related to U.S. patentapplication Ser. No. 11/888,341, filed simultaneously herewith, entitledMETHOD FOR REFURBISHING AN ELECTROSTATIC CHUCK WITH REDUCED PLASMAPENETRATION AND ARCING, and application Ser. No. 11/888,311, filedsimultaneously herewith, entitled METHOD AND APPARATUS FOR PROVIDING ANELECTROSTATIC CHUCK WITH REDUCED PLASMA PENETRATION AND ARCING. Theaforementioned related patent applications are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to equipment forperforming semiconductor device fabrication, and more particularly, toan electrostatic chuck for supporting a semiconductor wafer duringprocessing.

2. Description of the Related Art

Electrostatic chucks are widely used for providing support to substrates(also referred to herein as semiconductor wafers or wafers) withinsemiconductor processing equipment such as a plasma processing chamber.An electrostatic chuck generally holds a substrate in a stationaryposition during processing of the substrate, i.e., during materialdeposition or etching. Electrostatic chucks utilize capacitive andJohnsen-Rahbeck attractive forces for holding the substrate in position.

One type of electrostatic chuck includes a body and a fluid distributionelement covered with a layer of a dielectric material thereby forming asupport surface. The body is generally conductive such that the bodyforms an electrode of the electrostatic chuck. A substrate is placedonto the support surface. The fluid distribution element includes aplenum that carries the fluid multiple passages formed in the supportsurface of the electrostatic chuck for distributing a heat transferfluid such as a gas between the support surface of the chuck and thebackside of the substrate. Generally, the gas fills the interstitialarea between the electrostatic chuck and the substrate, thus enhancingthe rate and uniformity of heat transfer between electrostatic chuck andthe substrate.

In plasma processing chambers, the electrostatic chuck is subjected tohigh power radio frequency (RF) fields and high density plasmas in thevicinity of the substrate. In such plasma processing chambers, it ispossible to have the gas breakdown due to high electric field generationin the gas passages. The operation and service life of the electrostaticchuck is adversely affected by plasma formation in the gas passages.Such plasma may damage the substrate, the electrostatic chuck or both.Furthermore, plasma formation in a gas passage can lead to arcing thatforms particulate contaminants in the chamber.

There exist various techniques for reducing the plasma formation in gaspassages. One technique includes inserting a porous dielectric plug intothe passage at the surface of the chuck. The porosity of the plug isselected to ensure a dimension of the pores inhibits plasma formation,yet allows the heat transfer fluid to reach the substrate supportsurface. While the porous material provides protection against plasmaformation, fabrication of such electrostatic chucks is difficult, timeconsuming and costly.

Accordingly, there is a need for an improved electrostatic chuck thatreduces plasma formation and arcing.

SUMMARY

Embodiments of the invention comprise a method of making anelectrostatic chuck comprising positioning a plate into a channel in abody to form a plenum and inserting a dielectric component into anopening in the plate, where the dielectric component defines a portionof a passage from the plenum. Thereafter, depositing a dielectric layercovering at least a portion of the body and at least a portion of theplate to form a support surface. The dielectric layer is polished to aspecified thickness. In one embodiment, the polishing process forms anopening through the dielectric layer to enable the dielectric componentto define a passage between the support surface and the plenum. Inanother embodiment, at least a portion of the dielectric layer is porousproximate the dielectric component such that the porous dielectric layerand the dielectric component form a passage between the support surfaceand the plenum. In a further embodiment, a hole is formed through thedielectric layer and the hole in the dielectric layer and the dielectriccomponent form a passage between the support surface and the plenum.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 illustrates a plasma-based substrate processing system comprisingan electrostatic chuck having a fluid distribution element according tovarious embodiments of the present invention;

FIG. 2 illustrates a top view of the electrostatic chuck of FIG. 1;

FIG. 2A illustrates a partial sectional perspective view of a portion ofthe electrostatic chuck of FIG. 2;

FIG. 3 illustrates a cross-sectional view of the electrostatic chuck ofFIG. 2 along the line 3-3;

FIG. 4 depicts a cross-sectional view of a fluid distribution element ofan electrostatic chuck according to one embodiment of the presentinvention;

FIG. 5 depicts a cross-sectional view of a fluid distribution element ofan electrostatic chuck according to another embodiment;

FIG. 6 depicts a cross-sectional view of a fluid distribution elementfor an electrostatic chuck according to another embodiment;

FIG. 7 depicts a cross-sectional view of a fluid distribution element ofan electrostatic chuck according to yet another embodiment of thepresent invention;

FIG. 8 depicts a cross-sectional view of a fluid distribution element ofan electrostatic chuck according to various embodiments of the presentinvention;

FIG. 9 depicts a cross-sectional view of a fluid distribution element ofan electrostatic chuck according to various embodiments of the presentinvention; and

FIG. 10 depicts a cross-sectional view of a fluid distribution elementof an electrostatic chuck according to various embodiments of thepresent inventions.

While the invention is described herein by way of example using severalembodiments and illustrative drawings, those skilled in the art willrecognize that the invention is not limited to the embodiments ofdrawing or drawings described. It should be understood that the drawingsand detailed description thereto are not intended to limit the inventionto the particular form disclosed, but on the contrary, the invention isto cover all modification, equivalents and alternatives falling withinthe spirit and scope of the present invention as defined by the appendedclaims. The headings used herein are for organizational purposes onlyand are not meant to be used to limit the scope of the description orthe claims. As used throughout this application, the word “may” is usedin a permissive sense (i.e., meaning having the potential to), ratherthan the mandatory sense (i.e., meaning must). Similarly, the words“include,” “including,” and “includes” mean including, but not limitedto. Further, the words “a” or “an” means “at least one” unless otherwisementioned.

DETAILED DESCRIPTION

FIG. 1 illustrates a plasma-based substrate processing system 36comprising an electrostatic chuck 68 according to various embodiments ofthe present invention. The plasma processing system 36 is used fortemperature controlled processing of substrates, such as Silicon wafers,GaAs wafers and the like, while creating and maintaining a plasmaenvironment in which to process the substrates. The plasma is created inthe vicinity of the substrate for processing the substrate, and thetemperature of the substrate is controlled using various techniques,such as, by supplying a heat transfer fluid to the back surface of thesubstrate. Although one embodiment of a plasma processing chamber isdescribed illustratively in a high density plasma-chemical vapordeposition (HDP-CVD) system such as the 300 mm HDP-CVD Ultima X systemavailable from Applied Materials, Inc. of Santa Clara, Calif., theinvention has utility in other process chambers where plasma is usedincluding physical vapor deposition chambers, chemical vapor depositionchambers, etch chambers and other applications where a temperaturecontrol of a substrate is desired.

FIG. 1 illustrates one embodiment of a HDP-CVD system 36, in which anelectrostatic chuck 68 is used to secure a substrate during processing.In accordance with embodiments of the present invention, theelectrostatic chuck 68 is designed to reduce plasma penetration andarcing proximate the chuck 68.

The system 36 includes a process chamber 38, a vacuum system 40, asource plasma system 42, a bias plasma system 44, a gas delivery system46, and a remote plasma cleaning system.

An upper portion of process chamber 38 includes a dome 50, which is madeof a dielectric material, such as alumina or aluminum nitride. The dome50 defines an upper boundary of a plasma processing region 52. Theplasma processing region 52 is bounded on the bottom by the uppersurface of substrate 54 and the substrate support member 56.

A heater plate 58 and a cold plate 60 surmount, and are thermallycoupled to, the dome 50. The heater plate 58 and the cold plate 60 allowcontrol of the dome temperature to within about +/−10 degree Centigradeover a range of about 100 to 200 degree Centigrade. This allowsoptimizing the dome temperature for the various processes. For example,it may be desirable to maintain the dome at a higher temperature forcleaning or etching processes than for deposition processes. Accuratecontrol of the dome temperature also reduces the flake or particlecounts in the process chamber and improves adhesion between thedeposited layer and the substrate.

The lower portion of process chamber 38 includes a body member 62, whichjoins the process chamber to the vacuum system. A base portion 64 of thesubstrate support member 56 is mounted on, and forms a continuous innersurface with, body member 62. Substrates are transferred into and out ofprocess chamber 38 by a robot blade (not shown) through aninsertion/removal opening 95 in the side of process chamber 38. Apneumatic actuator (not shown) raises and lowers a lift-pin plate (notshown) that raises and lowers lift pins (not shown) that raise and lowerthe wafer. Upon transfer into process chamber 38, substrates are loadedonto the raised lift pins, and then lowered to a substrate receivingportion 66 of substrate support member 56. Substrate receiving portion66 includes an electrostatic chuck 68 that secures the substrate tosubstrate support member 56 during substrate processing.

The vacuum system 40 includes a throttle body 70, which housesmulti-blade throttle valve 72 and is attached to gate valve 74 andturbomolecular pump 76. It should be noted that throttle body 70 offersminimum obstruction to gas flow, and allows symmetric pumping, asdescribed in co-pending, commonly assigned United States patentapplication, originally filed on filed Dec. 12, 1995, and assigned Ser.No. 08/574,839, refiled on Sep. 11, 1996 and assigned Ser. No.08/712,724 entitled “SYMMETRIC CHAMBER”. The gate valve 74 can isolatethe pump 76 from the throttle body 70, and can also control processchamber pressure by restricting the exhaust flow capacity when throttlevalve 72 is fully open. The arrangement of the throttle valve 72, gatevalve 74, and turbo molecular pump 76 allow accurate and stable controlof process chamber pressures from about 1 to 100 millitorr.

The source plasma system 42 includes a top coil 78 and side coil 80,mounted on dome 50. A symmetrical ground shield (not shown) reduceselectrical coupling between the coils. Top coil 78 is powered by top RFsource generator 82, while the side coil 80 is powered by side RF sourcegenerator 84, allowing independent power levels and frequencies ofoperation for each coil. This dual coil system allows control of theradial ion density in process chamber 38, thereby improving plasmauniformity. Side coil 80 and top coil 78 couple energy into the chamber38 inductively. In a specific embodiment, the top RF source generator 82provides up to 8000 W of RF power at nominally 2 MHz and the side RFsource generator 84 provides up to 8000 W of RF power at nominally 2MHz. The operating frequencies of the top and side RF generators may beoffset from the nominal operating frequency (e.g., to 1.7-1.9 MHz and1.9-2.1 MHz, respectively) to improve plasma-generation efficiency.

The RF generators 82 and 84 include digitally controlled synthesizersand operate over a frequency range from about 1.7 to about 2.1 MHz. Eachgenerator includes an RF control circuit (not shown) that measuresreflected power from the process chamber and coil back to the generator,and adjusts the frequency of operation to obtain the lowest reflectedpower, as understood by a person of ordinary skill in the art. RFgenerators are typically designed to operate into a load with acharacteristic impedance of 50 ohms. RF power may be reflected fromloads that have a different characteristic impedance than the generator.This can reduce power transferred to the load. Additionally, powerreflected from the load back to the generator may overload and damagethe generator. Because the impedance of a plasma may range from lessthan 5 ohms to over 900 ohms, depending on the plasma ion density amongother factors, and because reflected power may be a function offrequency, adjusting the generator frequency according to the reflectedpower increases the power transferred from the RF generator to theplasma and protects the generator. Another way to reduce reflected powerand improve efficiency is with a matching network.

Matching networks 89 and 90 match the output impedance of generators 82and 84 with coils 78 and 80, respectively. The RF control circuit maytune both matching networks by changing the value of capacitors withinthe matching networks to match the generator to the load as the loadchanges. The RF control circuit may tune a matching network when thepower reflected from the load back to the generator exceeds a certainlimit. One way to provide a constant match, and effectively disable theRF control circuit from tuning the matching network, is to set thereflected power limit above any expected value of reflected power. Thismay help stabilize a plasma under some conditions by holding thematching network constant at its most recent condition.

The bias plasma system 44 includes a RF bias generator 86 and a biasmatching network 88. The bias plasma system 44 capacitively couplessubstrate receiving portion 66 to the body member 62, which act ascomplementary electrodes. The bias plasma system 44 serves to enhancethe transport of plasma species created by the source plasma system 42to the surface of the substrate. In a specific embodiment, the RF biasgenerator 86 provides up to 10000 W of RF power at 13.56 MHz.

Other measures may also help stabilize a plasma. For example, the RFcontrol circuit can be used to determine the power delivered to the load(plasma) and may increase or decrease the generator output power to keepthe delivered power substantially constant during deposition of a layer.

The gas delivery system 46 includes a plurality of gas sources 100 a,100 b, 100 c, 100 d and 100 e. In one embodiment, the aforementioned gassources comprise of silane, molecular oxygen, helium and argon,respectively. The gas delivery system 46 provides gases from severalsources to the process chamber for processing the substrate via gasdelivery lines 92 (only some of which are shown). Gases are introducedinto the process chamber 38 through a gas ring 94, a top nozzle 96, anda top vent 98. Specifically, gas sources, 100 a and 100 d, provide gasto top nozzle 96 via flow controllers 120 a and 120 c, respectively, andgas delivery lines 92. Gas from gas source 100 b is provided to gas vent98 via flow controller 120 b. The top nozzle 96 and top vent 98 allowindependent control of top and side flows of the gases, which improvesfilm uniformity and allows fine adjustment of the film's deposition anddoping parameters. The top vent 98 is an annular opening around the topnozzle 96 through which gas may flow into the process chamber from thegas delivery system.

Gas is provided from each of the aforementioned gas sources to gas ring94 via flow controller 102 a, 102 b, 102 c, 102 d and 102 e and gasdelivery lines 92. Gas ring 94 has a plurality of gas nozzles 106 and108 (only two of which is shown) that provide a uniform flow of gas overthe substrate. Nozzle length and nozzle angle may be changed by changinggas ring 94. This allows tailoring the uniformity profile and gasutilization efficiency for a particular process within an individualprocess chamber. In a specific embodiment, the gas ring 94 has a totalof thirty-six gas nozzles, twenty-four first gas nozzles 108 and twelvesecond gas nozzles 106. Typically, gas nozzles 108 (only one of which isshown), are coplanar with, and shorter than, the second gas nozzles 106.

In some embodiments, flammable, toxic, or corrosive gases may be used.In these instances, it may be desirable to eliminate gas remaining inthe gas delivery lines after a deposition. This may be accomplishedusing a three-way valve, such as valve 112, to isolate process chamber38 from delivery line 92 a, and to vent delivery line 92 a to vacuumforeline 114, for example. As shown in FIG. 1, other similar valves,such as 112 a and 112 b, may be incorporated on other gas deliverylines. Such three-way valves may be placed as close to process chamber38 as practical, to minimize the volume of the unvented gas deliveryline (between the three-way valve and the process chamber).Additionally, two-way (on-off) valves (not shown) may be placed betweena mass flow controller (MFC) and the process chamber or between a gassource and an MFC.

The system 36 may further include a remote cleaning RF plasma source(not shown) for providing a cleaning gas to the top nozzle 96 of thechamber 38. In other embodiments, cleaning gas (if used) may enter thechamber 38 at other locations.

A system controller 132 regulates the operation of system 36 andincludes a processor 134 in electrical communication therewith toregulate the operations thereof. Typically, the processor 134 is part ofa single-board computer (SBC), that includes analog and digitalinput/output boards, interface boards and stepper motor controllerboards. Various components of the CVD system 36 conform to the VersaModular European (VME) standard, which defines board, card cage, as wellas connector type and dimensions. The VME standard also defines the busstructure as having a 16-bit data bus and a 24-bit address bus. Theprocessor 134 executes system control software, which is a computerprogram stored in a memory 136, electronically coupled to the processor134. Any type of memory device may be employed, such as a hard diskdrive, a floppy disk drive, a card rack or a combination thereof. Thesystem control software includes sets of instructions that dictate thetiming, mixture of gases, process chamber pressure, process chambertemperature, microwave power levels, pedestal position, and otherparameters of a particular process

Temperature of the substrate 104 and uniformity of the substratetemperature are important processing parameters for processing thesubstrate 104. To generate a uniform temperature profile, a heattransfer fluid is applied between the chuck 68 and the back surface ofthe substrate 104. One embodiment of the invention uses, for example,helium as the heat transfer fluid. Generally, the electrostatic chuck 68is circular in shape, but alternatively, the electrostatic chuck 68 maycomprise various regular and irregular geometries to accommodatenon-circular substrates, for example, square or rectangular substratesuch as flat panels.

In operation, the substrate 104 is placed on the electrostatic chuck 68and multiple gaseous components are supplied from gas panel 46 into theprocessing region 52 of the plasma processing chamber 38 to form agaseous mixture. To ignite a plasma, RF power is applied to one or moreof an electrode in the substrate support member 56, the top coil 78, orside coil 80. To maintain temperature uniformity of the substrate duringprocessing, a heat transfer fluid, such as helium gas, is supplied viaat least one fluid distribution element (shown and discussed below) inaccordance with the embodiments of the present invention.

FIG. 2 illustrates a top plan view of the electrostatic chuck 68 havingthe fluid distribution element 222 according to one embodiment of thepresent invention. FIG. 2A depicts a partial sectional perspective viewof the electrostatic chuck 68 of FIG. 2. FIG. 3 depicts across-sectional view of the chuck 68 of FIG. 2 taken along line 3-3. Thefollowing disclosure is best understood by simultaneously viewing FIGS.2 and 3. The electrostatic chuck 68 comprises a body 220, a fluiddistribution element 222, and a dielectric layer 224. In one embodimentof the electrostatic chuck 68, the body 220 is fabricated of aconductive material such as aluminum and the dielectric layer 224 is aceramic material such as aluminum-nitride, alumina, and the like. Thefluid distribution element 222 is disposed circumferentially near theperiphery of the electrostatic chuck 68. The fluid distribution element222 comprises multiple holes 230 (or other forms of passages)penetrating the dielectric layer 224 for distributing a fluid such ashelium gas from the electrostatic chuck to the back surface of thesubstrate. For the electrostatic chuck 102 used in combination with a 12inch (300 mm) diameter semiconductor wafer, there are between 60 to 360holes around the periphery of the electrostatic chuck 102. Each of themultiple holes 230 typically ranges from about 0.15 mm diameter. Thesedimensions are adjusted depending on the kind of fluid distributionelement used, the pressures used within the processing chamber, and theamount of gas flow through the fluid distribution element 222.

The fluid distribution element 222 has a ring-shaped structure. However,in alternate embodiments, the fluid distribution element 222 may havevarious geometrical designs as per the need of the processing methodsand a user including multiple rings, radial arms, combinations ofradials and rings, and so on. The embodiments of the invention do notlimit the geometry of the fluid distribution element or elements.

The dielectric layer 224 covers at least a portion of the top surface ofthe body 220 and at least a portion of the fluid distribution element222 thereby forming a support surface 228. The support surface 228supports the substrate 104 placed thereon. The dielectric layer 224 maybe sprayed onto the top surface of the body and polished to a desiredthickness.

The body 220 comprises the top surface 332 and a channel 334 that isformed into top surface 332 of the body 220. Generally, the channel 334has a rectangular cross-sectional shape. However, in alternateembodiments the channel 334 may have various geometrical cross-sectionalshapes. The fluid distribution element 222 is coupled to the body 220such that the channel 334 and the fluid distribution element 222 form aplenum 336 i.e., the element 222 is positioned into the channel 334 andfixed thereto. Further, the body 220 comprises a conduit 338 connectedto the channel 334 for providing fluids to the plenum 336. According toone embodiment of the present invention, the cooling gas may be suppliedthrough the conduit 338 and distributed by the plenum to the fluiddistribution element 222. The gas exits through one or more of themultiple holes 230 (or other forms of passages) thereby supplying a heattransfer medium to the back surface of a substrate.

FIGS. 4 to 10 illustrate cross-section views of the dotted line portion230 of an electrostatic chuck, for example, the electrostatic chuck 102,the portion having a fluid distribution element 222, dielectric layer228 and the body 220. In the illustrations, the dimensions of theelectrostatic chuck have been exaggerated to illustrate thecross-section of the fluid distribution element and the body.

In particular, FIG. 4 illustrates a portion of an electrostatic chuck402 according to one embodiment of the present invention. The body 220comprises a dual damascene channel 404 having a lower channel 404A andan upper channel 404B, where the lower channel 404A is narrower than theupper channel 404B. The electrostatic chuck 402 includes a fluiddistribution element 422 comprising a plate 440 and a dielectric tube442. The plate 440 fits into the upper channel 404B (e.g., the plate hasa circular plan form to match the channel 404) such that the base 406 ofthe upper channel 404B forms a stop. The height of the plate 440 issubstantially the same as the height of the upper channel 404B such thatthe top 408 of the plate 440 is substantially coplanar with the top 332of the body 220. The plate 440 may be fabricated of a conductivematerial such as aluminum and welded into place in the upper channel404B. The plate 440 further comprises a channel 410 formed in the bottomsurface of the plate 440. In one embodiment of the invention, the widthof channel 410 is substantially similar to the width of lower channel404A; however, in other embodiments, the channel 410 may have a narrowerwidth than lower channel 404A. The combination of the lower channel 404Aand the channel 410 defines a plenum 336.

A dielectric tube 442 (an electrical isolator) comprises a first end446, a second end 448, and an axial through hole 450. The dielectrictube 442, for example, made of alumina, has a diameter substantiallymatching the diameter of an opening 444 in the plate 440. The diameterof the opening 444 is generally, but not by way of limitation, about0.008 inches (about 0.2 mm) or larger. In alternate embodiments, theopening 444 may have various geometrical shapes such as circular,rectangular, square, and the like. Moreover, the shape and size of theopening substantially matches to the shape and size of an outer diameterof the dielectric tube 442. The dielectric tube 442 is positioned (e.g.,press fit) into the opening 444. The opening 444 comprises a flange 412upon which the tube 442 rests (i.e., the flange forms a stop). In thedepicted embodiment, the first end 446 of the tube 442 extends above thesurface 332 of the body 220. In other embodiments, the first end 446 ofthe tube 442 may be coplanar with the surface 332.

At least a portion of the body 220 and at least a portion of the fluiddistribution element 422 are covered by the dielectric layer 224 therebyforming the support surface 428. The dielectric layer 224 may be sprayedonto the top surface of the body and polished to a desired thickness. Inone embodiment, the dielectric layer 224 comprises thermally sprayedAlumina or sprayed Alumina/Titania. Processes for application of thisthermally sprayed dielectric layer are known in the art. The thermalspraying process can be selected from several different methods such asplasma spraying, detonation gun spraying, high velocity oxygen fuel(HVOF) spraying and flame spraying.

In one embodiment, the dielectric layer 224 is polished to a thicknessrepresented by line 414 such that the surface 428 of the layer 224 iscoplanar with the end 446 of the tube 442. Alternatively, the dielectriclayer 224 may be a porous ceramic such that the layer 224 is polished toa specific flatness, but the layer 224 covers at least the first end 446of the tube 442. Due to the porosity of the ceramic, gas from the plenumflows through the tube 442 and the dielectric layer 224. For example,the dielectric layer 224 proximate the first end 446 of the tube 442 maybe wholly or partially formed of alumina with a porosity of between 10and 60 percent by volume that results in pore diameters of about 1 to100 um. In some embodiments, as discussed below with respect to FIG. 8,the dielectric layer may be porous proximate the end 446 of the tube442, and less porous elsewhere. As illustrated, the passage 445advantageously lacks a direct line-of-sight path from the supportsurface 428 to the plenum 436 thereby limiting the potential forformation of a plasma in the passage 445. In another embodiment, thedielectric layer 224 is polished to a specific flatness with the layer224 covering the first end 446 of the tube 442. A hole 416 can be boredor otherwise formed (e.g., laser drilling) through the dielectric layer416 into the passage 445. The boring process only bores through thedielectric material, i.e., the conductive material of the body is notsputtered by the boring process.

As known in the art, the support surface 428 may further be processed toprovide a pattern of grooves (not shown in the figure) made onto thedielectric layer 224. The grooves are machined or otherwise formed intothe support surface 428 so that they intersect with the passage 445. Thecooling gas can proceed from passage 445 and into the grooves fordistributing the cooling gas uniformly over the entire support surface428 of electrostatic chuck 402.

By using an electrical isolator (the dielectric tube and/or thedielectric layer) to define the passage between the plenum and thesubstrate surface, the possibility for plasma formation from the heattransfer gas or arcing caused by plasma formation is reduced. Byreducing or eliminating plasma formation and arcing, the life of anelectrostatic chuck is significantly increased. The use of an isolator,reduces the electric fields in the passage; thus, reducing the chancefor plasma formation. In addition, certain embodiments of the inventionutilize a fluid distribution element structure that further reduces theelectric fields in the passage by eliminating a line of sight pathbetween the substrate support surface (where high electric fields exist)and the conductive surface of a plenum. When such a line-of-sight pathexists, the volume of fluid in the passage is sufficient to be ignitedinto a plasma. Using a non-line-of-sight path reduces the electricfields that are established across sufficiently large volumes of fluidthat might result in plasma formation. As such, plasma formation andassociated arcing are reduced or eliminated.

FIG. 5 illustrates a cross-section of a portion an electrostatic chuck502 according to another embodiment of the present invention. Similar tothe embodiment of FIG. 4, a dielectric tube 542 is positioned throughthe plate 440. In this alternative embodiment, the tube 542 extends tothe bottom of the channel 534 where a second end 548 of the tube 542rests upon a supporting element (e.g., a step 556) formed in the bottomof the channel 534. As in the previous embodiment, the dielectric tube542 and/or the portion of dielectric layer 224 forms an electricalisolator that defines a passage 545 for the fluid from a plenum 536 tothe surface 528.

FIG. 6 illustrates a cross-section of a portion the electrostatic chuck602 according to another embodiment of the present invention. Similar tothe embodiments of FIGS. 4 and 5, a dielectric tube 642 is positionedthrough the plate 440. In this alternative embodiment, the dielectrictube 642 comprises at least one notch 656 formed in the second end 604.In an alternative embodiment, the tube 642 may comprise holes tofacilitate fluid flow from the plenum 636 to a passage 645 in the tube642. As with prior embodiments, the dielectric layer 224 may be porousand cover a first end 606 of the tube 642, the layer 224 may be polishedto expose the first end 606 of tube 642, or a hole formed in the layerto access the passage 645. The dielectric tube 642 and the portion ofdielectric layer 224 forms a passage 645 for the fluid from a plenum636. As illustrated, when the dielectric layer 224 is porous and coversthe tube 642, the passage 645 advantageously lacks a directline-of-sight path from the support surface 628 to the plenum 636thereby limiting formation of a plasma in the passage 645.

FIG. 7 illustrates a cross-section of a portion of an electrostaticchuck 702 according to yet another embodiment of the present invention.The electrostatic chuck 702 comprises a body 720 and fluid distributionelement 722. The fluid distribution element 722 comprises a plate 740and a dielectric tube 742 that are assembled in the same manner as theprevious embodiments. In this embodiment, the body 720 comprises achannel 734 comprising a dielectric end cap 760. The dielectric end cap760 is positioned at the bottom of the channel 734. The dielectric endcap 760 comprises an opening 762 such that the cap 760 is cup shaped.The dielectric tube 742 comprises a first end 746, a second end 748, andan axial through hole 750 connecting the first end 746 and the secondend 748. In one embodiment of the invention, the dielectric layer 724covers the first end 746 of the tube 742 and, in a second embodiment,the dielectric layer 724 is polished to line 414 to expose the first end746 of the tube 742. The dielectric cap 760 is positioned into thechannel 734 such that the second end 748 of the tube 742 extends intothe opening 762, but is spaced apart therefrom to form a gap. The tube742 and the end cap 760 form a labyrinth channel through which the fluidflows. Using such a channel ensures that a line-of-sight path from theconductive plenum walls to the chuck surface does not exist.

FIG. 8 illustrates a cross-section of a portion an electrostatic chuck802 according to another embodiment of the present invention. Theelectrostatic chuck 802 comprises a fluid distribution element 822. Thefluid distribution element 822 comprises a plate 840 comprising anopening 844. The plate 840 is coupled to a body 820 such that a channel834 and the plate 840 form a plenum 836. A dielectric layer 824 coversat least a portion of the body 820 and at least a portion of the fluiddistribution element 822. The dielectric layer 824 comprises a porousdielectric segment 870 such that at least a portion of the porousdielectric segment 870 overlaps the opening 844. The porous dielectricsegment 870 is a porous ceramic, such as alumina having a porosityranging from about 10% in volume to about 60% in volume, withinterconnected openings that form continuous passageways through theporous dielectric segment 870. The opening 844 and at least a portion ofthe porous dielectric segment 870 form a passage 845 for the fluid toflow from the plenum 836 to the support surface 828 of the electrostaticchuck 802. As illustrated, the passage 845 advantageously lacks directline-of-sight path from the support surface 828 to the conductive plenum836 thereby inhibiting formation of a plasma into the passage 845.

FIG. 9 illustrates a cross-section of a portion an electrostatic chuck902 according to another embodiment of the present invention. Theelectrostatic chuck 902 comprises a fluid distribution element 922. Thefluid distribution element 922 comprises a plate 940 having an opening944 and a dielectric plug 980. The plate 940 is coupled to a body 920such that a channel 934 and the plate 940 form a plenum 936. The plate940 and body 920 are assembled as discussed above with respect to theother embodiments of the invention. Diameter of the dielectric plug 980substantially matches with the diameter of the opening 944. Thedielectric plug 980 is positioned in the opening 1044 and generallypress fit therein. The dielectric layer 224 covers at least a portion ofthe body 920 and at least a portion of the fluid distribution element922 thereby forming a support surface 928. The dielectric layer 224 maybe sprayed onto the top surface of the body 920 and the fluiddistribution element 922, and polished to a desired thickness. A hole982 is formed through the dielectric layer 224 and through thedielectric plug 980. The hole 982 enables flow of the fluid from theplenum 936 to the support surface 928 of the electrostatic chuck 902.The hole 982 may be formed using various techniques such as mechanicaldrilling, laser drilling and the like. The hole 982 is formed throughonly dielectric material. As such, no metallic residue from the drillingprocess can form on the axial through hole 982. Without such metallicresidue, the possibility of plasma formation or arcing in the hold 982is limited.

FIG. 10 illustrates a cross-section of a portion an electrostatic chuck1002 according to another embodiment of the present invention. Theelectrostatic chuck 1002 comprises a fluid distribution element 1022.The fluid distribution element 1022 comprises a plate 1040 and adielectric cap 1042. The plate 1040 comprises two circular rings 1040Aand 1040B. The ring 1040A has a smaller diameter than ring 1040B. Eachring 1040A and 1040B rests upon the ledge 406 formed at the bottom ofthe upper channel 404B. The plate 1040 is welded to the body 1020 toretain the plate in the upper channel 404B. The dielectric cap 1042(ring shaped to form the plenum 1036) is inserted into the upper channel404B and rests upon the plate 1040.

In another embodiment, the plate 1040 may comprise an inverted U-shapedcross-section (e.g., the plate 440 of FIG. 4) having a plurality ofcounter-sunk holes. A circular (donut-shaped) dielectric element havinga cross-section similar to the element 1042 may be inserted into such acounter-sunk hole. The fluid distribution element 1022 is coupled to abody 1020 such that the fluid distribution element 1022 and a channel1034 form a plenum 1036. The dielectric layer 224 covers at least aportion of the body 1020 and at least a portion of the fluiddistribution element 1022, thereby forming a support surface 1028. Thedielectric layer 224 may be sprayed onto the top surface of the body1020 and the fluid distribution element 1022 and polished to a desiredthickness. A hole 1082 is formed through the dielectric layer 224 andthe dielectric cap 1090. The hole 1082 may be drilled using varioustechniques such as mechanical drilling, laser drilling and the like. Aswith the embodiment of FIG. 9, the hole 1082 is formed throughdielectric material only. As such, no conductive residue remains in thehole 1082.

In each of the foregoing embodiments, in the unlikely occurrence that anelectrostatic chuck utilizing the inventive fluid distributionelement(s) is damaged by plasma formation or arcing, the chuck can beeasily repaired using a number of methods. Generally, a damaging plasmaformation or arcing will occur proximate or within a dielectriccomponent (tube, porous insert, and the like). As such, the dielectriclayer can be removed locally (over the dielectric component) or globally(across the entire chuck) to expose the dielectric component. Thecomponent can then be removed using an extraction tool to drill out orpull out the component. Once removed, a new dielectric component can beinserted and the dielectric layer replaced either locally or globally asneeded. In some embodiments, the dielectric component may extend to thesupport surface of the chuck (as discussed above) and not requireremoval of the dielectric layer before extraction. In those situation,the damaged dielectric component is removed and a new dielectriccomponent is inserted (generally press fit) into the opening in theplate. In this manner, an electrostatic chuck can be repaired atsubstantial savings when compared to replacing an entire electrostaticchuck upon arcing or plasma formation in or near the heat transfer fluidpassages.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method of making an electrostatic chuck comprising: positioning aplate into a channel in a body to form a plenum; inserting a dielectriccomponent into an opening in the plate, wherein the dielectric componentcomprises a dielectric tube comprising a first end, a second end and anaxial through hole connecting the first end and the second end;positioning a dielectric end cap within the channel and opposite theaxial through hole of the dielectric tube, wherein the second end of thedielectric tube is disposed inside of the dielectric end cap and whereina portion of the end cap extends transversely over the second end of thedielectric tube while being spaced apart therefrom to form a gap;depositing a dielectric layer covering at least a portion of the bodyand at least a portion of the plate to form a support surface; polishingthe dielectric layer to a specified thickness; and forming an openingthrough the dielectric layer and the dielectric component to define apassage between the support surface and the plenum, wherein the gap andthe axial through hole form the passage.
 2. The method of claim 1wherein at least a portion of the dielectric layer is porous.
 3. Themethod of claim 1 wherein the forming step comprises drilling a holethrough the dielectric layer to the dielectric component.
 4. The methodof claim 1 wherein the dielectric component comprises alumina.
 5. Themethod of claim 1 wherein the dielectric layer comprises alumina.
 6. Themethod of claim 1, wherein the dielectric end cap includes an openingdisposed in an end of the dielectric end cap, wherein the dielectrictube is disposed within the opening, and wherein a bottom of the openingopposes the axial through hole.
 7. The method of claim 1, furthercomprising: covering at least a portion of the first end with thedielectric layer, wherein at least a portion of the dielectric layerfurther forms the passage.
 8. The method of claim 7 wherein the formingstep comprises polishing the dielectric layer until the axial throughhole of the dielectric tube is exposed at the support surface.
 9. Themethod of claim 7 wherein at least a portion of the dielectric layerproximate the first end of the dielectric tube is porous.
 10. The methodof claim 1 wherein the body is conductive.
 11. The method of claim 10further comprising welding the plate into the channel.
 12. A method ofmaking an electrostatic chuck comprising: positioning a plate into achannel in a body to form a plenum; inserting a dielectric componentinto an opening in the plate, wherein the dielectric component comprisesa dielectric tube comprising a first end, a second end and an axialthrough hole connecting the first end and the second end; positioning adielectric end cap within the channel and opposite the axial throughhole of the dielectric tube, wherein the second end of the dielectrictube is disposed inside of the dielectric end cap and wherein a portionof the end cap extends traversely over the second end of the dielectrictube while being spaced apart therefrom to form a gap; depositing adielectric layer covering at least a portion of the body, at least aportion of the plate, and the dielectric component to form a supportsurface, where at least a portion of the dielectric layer proximate thedielectric component is porous; and polishing the dielectric layer to aspecified thickness, wherein the at least a portion of the dielectriclayer proximate the dielectric component, the gap, and the axial throughhole form a passage between the support surface and the plenum.
 13. Themethod of claim 12, further comprising: covering at least a portion ofthe first end with the dielectric layer, wherein at least a portion ofthe dielectric layer further forms the passage.
 14. The method of claim12 wherein the dielectric component comprises alumina.
 15. The method ofclaim 12 wherein the dielectric layer comprises alumina.
 16. The methodof claim 12, wherein the dielectric end cap includes an opening disposedin an end of the dielectric end cap, wherein the dielectric tube isdisposed within the opening, and wherein a bottom of the opening opposesthe axial through hole.
 17. The method of claim 12 wherein the body isconductive.
 18. The method of claim 12 further comprising welding theplate into the channel.